The present invention relates generally to the field of switches, and in particular, but not exclusively to switches for power tools. In this field it is known to use printed circuit carriers of the hybrid type, comprising a ceramic carrier, traces applied on said carrier and circuit components located on said carrier.
During the assembly of such switch units these carriers have to be located into the housing of the switch unit, after which the contacts for the switches have to be inserted, and finally the moving parts of the switch. This involves labour-intensive and thus costly processing.
The aim of the invention is to provide such a switch, and in particular a printed circuit carrier fit for use in said switch, wherein the assembly of a switch unit can be automated, for instance through the use of pick and place apparatuses.
This aim is reached in that fixed contacts belonging to a switch are applied on the circuit carrier.
The application of at least a part of the fixed contacts of the switch allow these contacts to be located on the carrier in the same process as the location of the other components to be located on the carrier, which can easily be executed through a pick-and-place apparatus.
This avoids labour-intensive manual processing.
According to a first embodiment the fixed contacts of the switch are soldered or brazed onto the carrier. This allows the use of the same soldering process, as is used of soldering the other components onto the carrier. It thus eliminates another processing step.
According to another preferred embodiment contact elements for a plug connection with wires are applied on the carrier.
The location of those contact elements onto said carriers obviates the need for screw connections, etcetera for making electrical connections with the switch unit, which classicly are formed by wires.
By using a plug connection with the wires the extra handling of the labour for screw connections are obviated, also eliminating an internal connection between the carrier in the housing of the switch unit, in which usually the screw connection elements have been provided.
Preferably, the contact elements have been brazed or soldered onto said carrier.
This offers the same advantages, as the soldering or brazing of the fixed contacts.
According to another prefered embodiment the contact elements and the contacts have the same shape.
This allows substantial savings in stock-keeping, etcetera.
According to another prefered embodiment the contacts are composed of a U-shaped profile of copper containing metal.
The use of this shape allows the multi-functionality of fixed contacts of a switch and of the contact pieces for plug connection by the same pieces. Further, the use of a copper containing metal combines the advantages of the low-electrical resistance of copper with other desirable quantities provided by another free selectable material.
According to yet another prefered embodiment the contact locations of the contacts are covered with a layer of a precious metal.
Other prefered embodiments appear from the other subclaims.